Bringing A Swap Meet 3D Printer Back From The Dead

February 10, 2020 by Tom Nardi 9 Comments

At a recent swap meet, [digitalrice] found what appeared to be a like-new QIDI X-Plus 3D printer. It wasn’t clear what was wrong with it, but considering it retails for $900 USD, he figured the asking price of $150 was worth the gamble. As you might expect, the printer ended up being broken. But armed with experience and a supply of spare parts, he was able to get this orphaned machine back up and running.

The first and most obvious problem was that the printer’s Z axis didn’t work properly. When the printer tried to home the axis, one of the motors made a terrible noise and the coupler appeared to be spinning backwards. From his experience with other printers, [digitalrice] knew that the coupler can slip on the shaft, but that didn’t appear to be the case here. Removing the stepper motor and testing it in isolation from the rest of the machine, he was able to determine it needed replacing.

Unfortunately, the spare steppers he had weren’t actually the right size. Rather than waiting around for the proper one to come in the mail, he took an angle grinder to the stepper’s shaft and cut off the 5 mm needed to make it fit, followed by a few passes with a file to smooth out any burrs. We’re not sure we’d recommend this method of adjustment under normal circumstances, but we can’t argue with the results.

The replaced Z motor got the printer moving, but [digitalrice] wasn’t out of the woods yet. At this point, he noticed that the hotend was hopelessly clogged. Again relying on his previous experience, he was able to disassemble the extruder assembly and free the blob of misshapen PLA, leading to test prints which looked very good.

But success was short lived. After swapping to a different filament, he found it had clogged again. While clearing this second jam, he realized that the printer’s hotend seemed to have a design flaw. The PTFE tube, which is used to guide the filament down into the hotend, didn’t extend far enough out. Right where the tube ended, the filament was getting soft and jamming up the works. With a spare piece of PTFE tube and some manual reshaping, he was able to fashion a new lining which would prevent the filament from softening in this key area; resulting in a more reliable hotend than the printer had originally.

It’s great to see this printer repaired to working condition, especially since it looks like [digitalrice] was able to fix a core design flaw. But a broken 3D printer can also serve as the base for a number of other interesting projects, should you find yourself in a similar situation. For example, replacing the extruder assembly with a digital microscope can yield some very impressive results.

Lathe And 3D Printer Help Repair Buried Buttons

February 3, 2020 by Tom Nardi 24 Comments

Usually corroded buttons on a piece of electronic equipment wouldn’t be that big a deal to repair, but as [Haris Andrianakis] recently found out, things can get a little tricky when they are sealed inside a device meant to operate in a marine environment. Figuring out how to get into the case to clean the buttons up is only half the battle, when you’re done you still need to close it back well enough that the elements can’t get in.

The device in question is a tachometer intended for a Yamaha outboard motor, and the buttons are sealed between the guage’s face and the compartment in the rear that holds the electronics. Pulling the guts out of the back was no problem, but that didn’t get [Haris] any closer to the defective buttons. In light of the cylindrical design of the gauge, he decided to liberate the front panel from the rest of the unit with his lathe.

Removing the face was a delicate operation, to put it mildly. The first challenge was getting the device mounted securely in the chuck, but then the cutting had to be done very carefully so as not to damage the housing. Once he cut through the side far enough to get the face off, the actual repair of the buttons was fairly straightforward. But how to get it back together?

After a few missteps, [Haris] finally found a solution that have him the results he was looking for. He 3D printed a ring that fit the front of the gauge tightly, hot glued it into place, and used it as a mould to pour in black epoxy resin. Once the epoxy had cured, the mould was cut off and the gauge went back on the lathe so he could trim away the excess. He had to do some hand sanding and filing to smooth out the bezel, but overall the end result looks very close to factory.

We get it, there’s a lot to consider when you add a lathe to your workshop. But hacks like these are wonderful reminders of how many tricks these versatile machines are really capable of.

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Fixing The Flicker Afflicting A Night Light

January 31, 2020 by Kristina Panos 11 Comments

It’s hard to part with some things, even if they’re broken and were worth next to nothing to begin with. But some things are just special, y’know? And we would say in this case, the thing was definitely worth saving.

[Taste the Code]’s daughter’s beloved night light had a terrible flickering problem, and then stopped working altogether. Eager to make her happy, he cracked it open and found that one of the wires had disconnected from the outlet pin it was soldered to. That’s a simple enough fix, but trying to solder in tight quarters where the walls are soft plastic can be quite challenging.

Once that was fixed, [Taste the Code] plugged it in to a test outlet. It’s back to working, but also back to flickering, because there is no capacitor to smooth out the signal going to the LEDs. [Taste the Code] measured the voltage drop across the output of the bridge rectifier and soldered in an electrolytic cap with more than double the necessary voltage rating, just to be safe. You can check out the video after the break.

This goes to show several things: one, you can learn from fixing and improving cheap electronics from the likes of your local dollar store. Two, you can also get some kinds of components there quite inexpensively from things like magnetic sensor-based window alarms and dirt cheap solar garden lights.

You can also do some fun stuff with those cheap IKEA lamps designed for children. Here’s an adorable cloud lamp with an RGB LED upgrade that shows the weather mood using an ESP8266.

Continue reading “Fixing The Flicker Afflicting A Night Light” →

Tidy Board Rework Uses Flex PCBs, No Wires

December 17, 2019 by Donald Papp 26 Comments

PCB rework for the purpose of fixing unfortunate design problems tends to involve certain things: thin wires (probably blue) to taped or glued down components, and maybe some areas of scraped-off soldermask. What are not usually involved are flexible PCBs, but [Paul Bryson] shows us exactly how flex PCBs can be used to pull off tricky rework tasks.

It all started when [Paul] had a run of expensive PCBs with a repeated error; a design mistake that occurred in several places in the board. Fixing with a bunch of flying wires leading to some glued-on components just wasn’t his idea of tidy. A more attractive fix would be to make a small PCB that could be soldered in place of several of the ICs on the board, but this idea had a few problems: the space available into which to cram a fix wasn’t always the same, and the footprints of the ICs to be replaced were too small to accommodate a PCB with castellated mounting holes as pads anyway.

It’s about then that he got a visit from the Good Idea Fairy, recalling that fab houses have recently offered “flex” PCBs at a reasonable cost. By mounting the replacement parts on a flex PCB, the board-level connection could reside on the other end of an extension. Solder one end directly to the board, and the whole flexible thing could be bent around or under on a case-by-case basis, and secured in whatever way made sense. Soldering the pads of the flex board to the pads on the PCB was a bit tricky, but easy enough to pull off reliably with a bit of practice. A bonus was that the flex PCB is transparent, so solder bridges are easy to spot. He even mocked up a solution for QFP packages that allows easy pin access.

Flex PCBs being available to hobbyists and individuals brings out fresh ideas and new twists on old ones, which is why we held a Flexible PCB Design Contest earlier this year. Repairs were definitely represented as applications, but not to the extent that [Paul] has shown. Nice work!

WWII Aircraft Radio Roars To Life: What It Takes To Restore A Piece Of History

December 12, 2019 by Gregory L. Charvat 59 Comments

I’ve been told all my life about old-timey Army/Navy surplus stores where you could buy buckets of FT-243 crystals, radio gear, gas masks, and even a Jeep boxed-up in a big wooden crate. Sadly this is no longer the case. Today surplus stores only have contemporary Chinese-made boots, camping gear, and flashlights. They are bitterly disappointing except for one surplus store that I found while on vacation in the Adirondacks: Patriot of Lake George.

There I found a unicorn of historical significance; an un-modified-since-WW2 surplus CBY-46104 receiver with dynamotor. The date of manufacture was early-war, February 1942. This thing was preserved as good as the day it was removed from its F4F Hellcat. No ham has ever laid a soldering iron or a drill bit to it. Could this unit have seen some action in the south Pacific? Imagine the stories it could tell!

My unconventional restoration of this radio followed strict rules so as to minimize the evidence of repair both inside and out yet make this radio perform again as though it came fresh off the assembly line. Let’s see how I did.

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Rescue An Expensive Servo With Some Reverse Engineering

December 11, 2019 by Donald Papp 9 Comments

[Andrew] had a servo damaged by someone connecting the power supply to the wrong pins (whoops) which fried the microcontroller and a logic level shifter. With a bit of reverse engineering, he successfully restored basic servo functionality by writing some new code. The new code implements only basic features, but that’s enough to save the device from the junk bin.

FAULHABER 2232DBHHO ring any bells? Google came up empty.

Why bother reverse engineering a servo? Well, if dollars are reasons then there are many for saving a HerkuleX DRS-0602 from the junk heap; they cost around 320 USD before shipping. Another reason to try is that the microcontroller turned out to be an AVR XMega, which gave [Andrew] confidence in writing some new code.

If you want to understand more about how these servos work, [Andrew] provides good photos of the insides and identifies the major components and their connections and functions. There are some mysteries (such as details of the motor and embedded encoder, which are FAULHABER 2232DBHHO) but [Andrew] figured out enough to write some basic code to allow the servo to work as a standard servo with a UART interface.

Sometimes curiosity drives reverse engineering and repair efforts, sometimes it’s cost, and sometimes it’s both. A $320 servo is certainly worth trying to save, and so are huge observatory telescopes with obsolete servo amps.

Restoring A Dead Commodore 128DCR

December 4, 2019 by Tom Nardi 11 Comments

Another day, another retro computer lovingly restored to like-new condition by [Drygol]. This time, the subject of his attention is a Commodore 128DCR that earned every bit of the “For Parts, Not Working” condition it was listed under. From a spider infestation to a cracked power supply PCB, this computer was in quite a state. But in the end he got the three decade old machine back in working condition and even managed to teach it a few new tricks along the way.

Obviously the shattered PSU was the most pressing issue with the Commodore. Interestingly, the machine still had its warranty seal in place on the back, so whatever happened to this PSU seems to have occurred without human intervention.

Rather than just replacing the PSU, [Drygol] first pieced the board back together with the help of cyanoacrylate glue, and then coated the top with an epoxy resin to give it some mechanical strength. On the back side the traces were either repaired or replaced entirely with jumper wires where the damage was too severe.

With the PSU repaired and tested, he moved on to cleaning the computer’s main board and whitening all the plastic external components. Even the individual keycaps took a bath to get them looking like new again. This put the computer in about as close to like-new condition as it could get.

But why stop there? He next installed the JiffyDOS modification to improve system performance, and wired in an adapter that lets the computer output a crisp 80 columns over S-Video. It’s safe to say this particular Commodore is in better shape now than it was when it rolled off the assembly line.

While an impressive enough final result, this is still fairly tame for [Drygol]. If you want to see a real challenge, take a look at the insane amount of work that went into recreating this smashed Atari 800XL case.